The purpose of this activity is to engage students in finding equivalent rates and interpreting the rates in context.
This activity assumes the students have experience in the following areas:
The problem is sufficiently open ended to allow the students freedom of choice in their approach. It may be scaffolded with guidance that leads to a solution, and/or the students might be given the opportunity to solve the problem independently.
The example responses at the end of the resource give an indication of the kind of response to expect from students who approach the problem in particular ways.
The Suds company have launched a new detergent. It will come in four bottle sizes, 400 mL, 900 mL, 1.2 L and 2.5 L, to suit customers’ lifestyles. Suds will sell the 1.2 L bottle for $7.80.
What prices should they charge for the other bottle sizes?
Justify why you set those prices.
The following prompts illustrate how this activity can be structured around the phases of the Mathematics Investigation Cycle.
Introduce the problem. Allow students time to read it and discuss in pairs or small groups.
Discuss ideas about how to solve the problem. Emphasise that, in the planning phase, you want students to say how they would solve the problem, not to actually solve it.
Allow students time to work through their strategy and find a solution to the problem.
Allow students time to check their answers and then either have them pair share with other groups or ask for volunteers to share their solution with the class.
The student uses proportional reasoning to establish prices for the three bottles.
Click on the image to enlarge it. Click again to close.
The student uses proportional relationships and context to establish prices for the three bottles.
Click on the image to enlarge it. Click again to close.
The student uses proportional relationships and context to establish prices for the three bottles.
Printed from https://nzmaths.co.nz/resource/washing-detergent-proportions at 1:51am on the 26th April 2024